If you want to get pixel-perfect results cross-browser, you may need to specify alternate stylesheets for different browsers, especially Internet Explorer. Internet Explorer doesn’t play by the same rules as most browsers.
Here is the basic technique for an IE-only stylesheet:
<!--[if IE]>
<link rel="stylesheet" type="text/css" href="ie-only.css"/>
<![endif]-->
You can also create IE-only stylesheets for specific versions of IE, for example,
<!--[if IE 7]>
<link rel="stylesheet" type="text/css" href="ie-7-only.css"/>
<![endif]-->
<!--[if IE 6]>
<link rel="stylesheet" type="text/css" href="ie-6-only.css"/>
<![endif]-->